The potentially harmful effects of overexposure to solar radiation are now well-documented. These harmful effects range from the discomfort of minor sunburn to increased incidences of serious disorders such as skin melanomas. A variety of methods for avoiding overexposure to the sun's rays have been devised. The use of hats, protective clothing, and other physical barriers to block radiation is common. A wide variety of chemical compounds are also available which can be used to block or absorb certain constituents of solar radiation. Such chemical compounds are widely used in suntan compositions. Such suntan compositions may be formulated to absorb a major portion of the incident radiation and screen the user from the sun's rays or they may be formulated to allow most of the radiation to pass through. The consumer can choose an appropriate level of sunscreen protection.
One problem frequently encountered by sunscreen users pertains to the difficulty in achieving complete and uniform protection. Uneven or incomplete application of sunscreen may result from the difficulty in applying lotion to hard-to-reach areas of the body such as the middle of the back. The back is not only hard to reach, but it is also hard to see, and therefore, it is often difficult to tell accurately where sunscreen has been applied. Even for portions of the body which are easy to reach and to see, it is often difficult to know where sunscreen has been applied because it is either clear as it is applied or it quickly becomes clear as it is rubbed into the skin. Thus, a common problem encountered by sunbathers or others who use sunscreen is the occurrence of localized areas of sunburn caused by the incomplete or uneven application of sunscreen. Such overexposure to the sun's rays can result in unattractive, uneven tanning and, more importantly, can lead to serious skin disorders if the overexposure is prolonged or particularly severe.
Another common problem faced by sunscreen users is knowing whether the sunscreen that had been applied at an earlier time is still present. Sunscreens are often formulated to be water-proof or water-resistant, but there are no guarantees as to just how water-resistant. Therefore, after several trips to and from the water, sunbathers cannot be certain their sunscreen has not washed away leaving them unprotected from the sun.
The subject invention provides, for the first time, an easy means for the sunscreen user to know exactly where sunscreen has, and has not, been applied and whether already applied sunscreen is still present. The technology of the subject invention can also be utilized in other situations where it is desired to know where a particular material has been applied. Clear lacquers, varnishes or sprays formulated with the temporary visual indicator of the subject invention allows the user to ensure that an area is adequately covered by these materials by providing a temporary color guide for the user during their application. The temporary visual indicator of the subject invention formulated with pesticides, herbicides or fertilizers guides the user in accurate and complete application of these materials to a treated area. In preparing for surgery or other medical procedure, it is often necessary or desirable to apply a disinfecting, medicated, or analgesic lotion or spray to a particular area of the patient. It is advantageous, or critical, to know precisely where that lotion or spray has been applied. The temporary visual indication of the subject invention ensures the entire surgical area is disinfected.
An adhesive compound which undergoes color changes upon application is described in Chandaria, U.S. Pat. No. 4,954,544. The indicator affecting the color change in '544 enhances the physical characteristics of the composition by contributing to the improved flow and adhesion of the glue. The indicator also adds to the economy of the product by allowing the glue to be formulated with less adhesive compound. Unlike the indicator in '544, the temporary visual indicator of the present invention is incorporated into a material exclusively to provide a visual guide for the application of that material to a surface. Until now there has been no accurate means for knowing the precise location where lotions or other like materials have been applied.